| 摘要 |
PURPOSE:To prevent degradation of weldablity and local corrosion of metal coated over the surface of an inner tube, by attaching the same metal as the metal coated over the surface of the inner tube or a metal having a poor potential to the top of each support employed for supporting the inner tube and an outer tube of a heat exchanger concentrically. CONSTITUTION:In supporting a inner tube 7 plated with zinc over the outer surface thereof and an outer tube 2 made of a low-carbon steel by supports 4 also made of a low-carbon steel which are welded at 6 to the outer tube 2, an aluminum piece 5 is attached to the top of each support 4, so that the support 4 are brought into contact with the outer surface of the inner tube 7 by the intermediary of the pieces 5. Resultantly, potential between the pieces 5 and the zinc plating of the inner tube 7 can be reduced considerably as compared with that developed between steel and zinc of the conventional arrangements. Therefore, it is enabled to prevent self- corrosion of zinc plating over the surface of inner tube 7 due to its pseudo-anodic function. |
